Centrifugally controlled variable resistance



R. J. BRIGHT Jam. 22, 1946.

CENTRIFUGALLY CONTROLLED VARIABLE RESISTANCE Filed Dec. 20, 1945INVENTOR BY y j! AT1-o RN EY Patented Jan. 22, 1946 UNITED STATES PATENTOFFICE CENTRIFUGAILY CONTROLLED VARIABILE yRESISTANCE Ray J. Bright, LosAngekes, Calif.

Application December 20, 1943, YSerial .o.5'15,'0'02 17 Claims.

This .invention relates to a variable resistance, and especially to onethat is varied in accordance with .speed variations.

In order to practice the invention, a conducting liquid is placed undertheinuenceof centrifugal force; and as .the .force varies due toavariation in speed, the liquid acts as .a movable contact .to vary theresistance. Preferably the .conducting liquid 4is mercury, .as it .hasobvious advantages for a centrifugally operateddevice.

vIt is one of the objects of this .invention to `provide a .resistancethat is continuously variable (as contrasted with one .that .is variedstep-bystep) over .a .substantial range, by the aid of a conductingliquid contact.

4It .is another object vof this invention to mak it possible .to adjustor calibrate the resistance in a. .simple manner.; that is, the value ofthe resistance at any .speed may be caused to assume any value betweenlimits.

It is still another .object of .my invention to provide a device of thischaracter in which the mercury is caused to assume a generally annularform about the .axis of rotation, the size of Vthe annulus being .alfunction vof the speed. This is walls of the chamber being yielding, sothat, as

the conducting liquid, .it `has a high coelcient ofexpansion as itk .issubjected .to temperature changes. lt .is still another object of thisinvention to compensate for the variation in volume of the mercury, andespecially by appropriate increase in the volume of `the chamber.

This invention vpossesses `many other .advantages, and has other objectswhich may be made more clearly apparent from a consideration of severalembodiments of the invention. For this purpose there are shown a few.forms in .the drawing accompanying and forming part of the presentspecification. These forms will now be described in detail, illustratingthe general principles of the invention; but .is to be understood thatthis .detailed description vis not to Ybe taken in alimiting.sense,.since the scope of the invention .is .best defined by theappended claims.

Referring to the drawing.:

Figure l is a longitudinal sectional View of an apparatus embodying theinvention;

Fig. 2 is asectional view taken along plane j2--2 of 1; f

Fig. 3 is a fragmentary sectional view, 'similar to Fig. .2, of .amodied.form of ythe invention; and

Fig. 4 .is a. view similar to F.ig` 3 .of a vfurther modified 4form .of.the .invention v .In .the .form of the invention .illustrated .in Figs.1 and 2, use is made of Aa .body of mercury l, serving as a conductingliquid. The mercury l is intended to be placed .under the .influence lofcentrifugal force, .as by .rotation about the axis 2. Under the .inuenceof this .centrifugal force, the body of mercury I assumes a generalannular form, .since it is conined vto that .annular 'form 'by the wallsof a chamber to .behereinater described.

.Upon variation of velocity Vabout the axis 2, Athe position of themercury annulus likewise changes. As the velocity decreases, the inneredge 3 of the annulus moves closer vto .the axis 2. Conversely, upon an.increase in velocity, this inner edge 3 moves .radially outwardly withrespect to the axis.

This movement is .made use of to control an electric circuit. Moreparticularly, it is used to vary the resistance lin the circuit in acontinuous manner.

The device is mounted for Yrotation upon an appropriate -shaftl25 by theaidl of a, metallic sleeve 4. A body 5 formed of a plastic, or otherinsulation material, is molded over the lefthand portion .of the outer.periphery of sleeve 4. For 4this purpose, .this left hand portion mayvbe roughened so as to provide an adequate fric'tional grip lbetween thebody 5 and the sleeve 4.

The body 5 carries .a pair of closely spaced walls 6 and 1extendingradially with .respect to the axis 2. The passageway 8 betweenthe opposed surfaces of these walls. forms a -space for the mercury l.The outer edge of the .body l .is oonfined yby a hollow yielding rubberring 9. .According-ly, as th'e liquid pressure increases within thehollow of the ring `9, .liquid pressure .is exerted by the mercury I inall directions against the inner surface of the ring 9, and causes 4thespace defined within .therlng to be increased. Inner edge 3 of themercury body l moves outwardly as the centrifugal force increases. vWhenthere Iis a decrease of liquid .pressure due to a .reduction in speed,the yielding ring .9 reduced the space available for the body of mercuryI and the inner edge 3 moves radially inwardly.

The hollow ring 9 is held in place by the aid of a copper sheathextending around the outer surface of the ring 9 and joined to the walls5 and 1. The outer edges of the walls 6 and 1 are provided withappropriate seats I3 and I4 engaging the inner edges of the ring 9. Thecopper sheath is formed in the present instance by the halves I and II.The inner edges of these halves are molded within the walls 6 and 1, andin the straight position illustrated in the lower portion of Fig. l bythe dot-dash lines. After ring 9 is placed in proper position, thehalves I0 and II are curved around the outer surface of the ring Si, andare joined by a crimped joint I2 along the outer periphery of the ring9. Furthermore, in oi'der to strengthen the insulation body 5, a num berof ribs or vanes 21 (Fig. l) may be provided extending from the wall 6,.

The body of mercury I serves to bridge the space between a pair ofconducting members I and I6. These conducting members are in the form ofhat metallic rings, embedded in the inner sides of walls 6 and 1, andhaving their opposed surfaces exposed in the chamber 8. The inner edgesof these members I5 and I6 are shown as embedded in the hub of body 5.Binding posts for making appropriate connection to the members I5 and I8may be provided as by the structures I1 and I8 respectively. Thesebinding posts may be formed by screws having their heads molded withinbody 5 and connected as by conductors IS and with the conductors I5 andI6 respectively.

The contact established between the metallic members I5 and IS may bebroken upon the exertion of a suilicient centrifugal force; in otherwords, the device may be used to interrupt or open a circuit upon theoccurrence of a definite speed of rotation by the axis 2. also possibleto utilize the variations in position of the inner edge 3 to vary theresistance included in an electric circuit joined to the binding postsI1 and I8.

For this purpose the metallic members I5 and IS may be formed ofresistance material, such' as nichrome. They may be provided with anumber of projections or teeth, such as indicated at 2I in Fig. 2. Theseteeth extend for a considerable radial distance. Accordingly, as theinner edge S of the mercury varies in its radial position, the circuitconnecting the binding posts I1 and I8 includes in parallel, a number ofteeth 2I, each of variable length. Outward movement to the edge 3introduces, accordingly, additional resistance in the circuit, becausean increased length of the teeth 2I is included in the circuit. Inwardmovement of the merculy edge 3 reduces the resistance, since the mercurythen extends closer to the roots of the teeth 2I.

Accordingly, there is a continuous variation in resistance as the speedof rotation varies about the axis 2.

It is possible by an inverted arrangement of teeth to cause theresistance to increase as the speed is reduced. Such an arrangement isdiagrammatically illustrated in Fig. 3. In this form the metallic member22 is shown as having radially inwardly directed teeth 23.

Accordingly, as the inner edge 3 moves outwardly, less and lessresistance is included in the circuit. As the edge 3 moves inwardly, theresistance increases.

The number and form of the extensions, such as 2I and 23, may be variedto suit th'e specific However, it is requirements of the control. In theform shown in Fig. 4, the extensions 24 are curved. The length of eachextension 24 is much greater than in the forms shown in Figs. 2 and 3.Accordingly, there is a greater variation of resistance from minimum tomaximum, as the inner edge 3 of the mercury body I moves outwardly,

It is apparent that the extensions, such as I5, 23, and 24, are allplaced in parallel between the binding posts I1 and I8 by the contactingmercury body I. By proper choice of the number of these extensions, thevalue of the resistance in the circuit may be determined.

Provisions are made for adjusting the volume of the chamber in which themercury I is located, so as to determine the position of inner edge 3,and thereby to adjust the absolute value of the resistance at any speed.For this purpose, the wall 1 is made iiexible. By urging the wall 1inwardly or toward the left, as viewed in Fig. l, the width of the space8 is reduced and the edge 3 of the mercury is accordingly caused to moveinwardly. To exert this exing force, use is made of a flange 25 threadedon the sleeve 4. This flange 25 has a projection 26 provided with aconvex surface engaging the wall 1. Operation of the flange 25 on thesleeve 4 serves to determine the pressure exerted against wall 1.

Temperature variations cause corresponding variations in the volume ofthe mercury I. This would result in undesired variations in theresistance, in accordance with temperature. By the use of the coppersheath IIJ-I I, these variations in volume of the mercury I are causedto be ineffective to vary the resistance. As the temperature increases,the copper sheath III-II expands and permits the flexible rubber ring 9to expand, increasing the volume of the hollow portion of the ring, andthus compensating for the increased volume of mercury. Conversely, areduction in temperature causes the rubber to contract and to reduce thevolume of the ring 9. The inner edge 3 of the mercury body I is thusmaintained in substantially the same place, independently of temperaturevariation.

The inventor claims:

l. In a device of the character described, a conducting liquid, rotarymeans for causing said liquid to be urged away by centrifugal force fromthe axis of rotation, a, conductor having a surface exposed to saidliquid, and means forming a yielding boundary for limiting the travel ofthe liquid from the axis.

2. In a device of the character described, a conducting liquid, andmeans .forming a rotary chamber for the liquid, a resistor in the formof a conductor having one or more extensions exposed to the liquid, saidchamber having yielding means defining a boundary for the liquid, fordetermining the position of the liquid with respect to the axis ofrotation of said chamber in accordance with the speed of rotation, saidextensions being so arranged that the position of contact between theliquid and the extension is determined by the position of the liquid inthe chamber.

3. In a device of the character described, a pair of resistor conductorshaving opposed surfaces denning a space, a conducting iquid bridging thesurfaces, a rotary support for the conductors, to cause the liquid to beurged by centrifugal force outwardly through said space, and a yieldingwall at the outer edge of the space.

4. In a device of the character described, a

pair yof resistor conductors each having one or more extensions, saidextensions having opposed surfaces defining a passage, a conductingliquid bridging the surfaces, a rotary support for the conductors, tocause the liquid to be urged by centrifugal force outwardly through saidpassage, anda yielding wall at the outer edge of the pas- 5.. In adevice of the cltalacter` described, a conducting liquid, means forminga rotaryA chamber for the liquid, a resistor in the form of a conductorhaving one or more extensions exposed to the liquid, said chamber havingyielding means defining a boundary for the liquid, for determining theposition of the liquid with respect to the axis of rotation of saidchamber in accordance with the speed of rotation, said extensions beingso arranged that the position of contact between the liquid and theextension is determined by the position of the liquid in the chamber,and means for supplementarily varying the volume of the chamber.

6. In a device of the character described, a conducting liquid, rotarymeans for. causing said liquid to be urged away by centrifugal forcefrom the axis of rotation, a conductor having a surface exposed to saidliquid, means forming a yielding boundary for limiting the travel of theliquid from the axis, and means acting on said yielding boundary, inresponse to temperature variations, for compensating for variations inthe volume of the liquid in accordance with the temperature.

7. In a device of the character described, a conducting liquid, meansforming a rotary chamber for the liquid, a resistor in the form of aconductor having one or more extensions exposed to the liquid, saidchamber having a yielding means defining a boundary for the liquid, fordetermining the position of the liquid with respect to the axis ofrotation of said chamber in accordance with the speed of rotation, saidextensions being so arranged that the positon of contact betweenl theliquid and the extension is determined by the position of the liquid inthe chamber, and means acting on said yielding means, in response totemperature variations, for enlarging the space for the liquid inaccordance with the temperature.

8. In a device of the character described, means forming a rotarychamber, said means including a flexible wall, a solid electricalconductor in the chamber, a liquid electrical conductor in the chamberfor co-operating with said solid conductor, means for altering theposition of the liquid with respect to the solid conductor, inaccordance with the speed of rotation of the chamber, and adjustablemeans for flexing said wall for altering the volume of the chamber andthereby supplementarily altering the position of the liquid.

9. In a device of the character described, means forming a rotarychamber having opposed walls forming a radially extending passageway,resistor conductors supported on the walls, a liquid electricalconductor in the passageway for connecting said conductors, one of saidwalls being flexible, and means for flexing said flexible Wall foraltering the volume of the chamber.

10. In a device of the character described, means forming a rotarychamber having opposed walls forming a radially extending passageway,resistor conductors supported on the walls, and a liquid electricalconductor in the passageway for connecting said conductors, said chamberincluding an annular recess in communication with said passageway, andformed of an elastic member, capable of expanding in response to fluidpressure exerted within. the recess by said liquid.

11. In a device of the character described, 5 means forming a. rotarychamber having opposed walls forming. a radially extending passageway,resistor conductors supported on the walls, a liquid conductor inthepassageway, saidV chamber including` an annular recessk incommunication. with .said passageway, and formed of an elasticmember,capable of expanding in response to fluid pressure exerted within theIrecess by said liquid, and a metallic sheath for said elastic member andhaving a coefficient of expansion such as to enlarge the recess as thetemperature increases, to provide compensation for expansion of theliquid.

12. In a device oi.' the character described, a metallic sleeve, a bodymounted on the sleeve and formed of insulation material and havingradially extending walls defining a space, one of said walls beingflexible, conductors carried by the walls and having surfaces exposed insaid space, a liquid electrical conductor in the space for connectingsaid conductors, and an adjusting member threaded on the sleeve andadapted to flex the flexible wall to vary the volume of the space.

13. In a device of the character described, a metallic sleeve, a bodymounted on the sleeve and formed of insulation material and havingradially extending walls defining a space, one of said walls beingflexible, resistor conductors carried by the walls and having surfacesexposed in said space, said surfaces having extensions, a liquidconductor adapted to form an annular conducting' bridge when the sleeveis rotated, the liquid bridge being capable of intersecting saidextensions at variable speeds of the sleeve, and means mounted on thesleeve for flexing said flexible wall to adjust the volume of saidchamber.

14. In a device of the character described, a

metallic sleeve, a body mounted on the sleeve and formed of insulationmaterial and having radially Y extending walls defining a space, one ofsaid Walls being flexible, resistor conductors' carried by the walls andhaving surfaces exposed in said space, said surfaces having extensions,a liquid conductor adapted to form an annular conducting bridge when thesleeve is rotated, elastic means defining an annular recess at the outeredge of said space, said liquid bridge thereby intersecting theextensions under the influence of varying speeds of rotation of thesleeve, and for a range of speed variations.

l5. In a device of the character described, a pair of rotatable,radially extending, axially spaced conductors, one of said conductorsbeing a resistor, the resistance of which is a function of the distanceof a connection to the resistor,

from the axis of rotation, and a conducting liquid resiliently confinedbetween said conductors, and adapted to form a surface movable radiallyoutwardly therebetween in response to rotation of said conductors, toconnect the conductors at a distance from the axis varying with thespeed of rotation, whereby said resistance varies in accordance withsaid speed.

16. In a device of the character described, a pair of rotatable,radially extending, axially spaced conductors, one of said conductorsbeing a resistor, the resistance of which is a function of the distanceof a connection to the resistor, from the axis of rotation, a conductingliquid resiliently confined between said conductors, and

of the distance of a connection to the resistor, from the axis ofrotation, means including a. resilient member encircling said conductorsforming a closed space between said conductors, and a conducting liquidin said space adapted to form a surface movable radially outwardlytherebetween in response to rotation of said conductors, to connect theconductors at a distance from the axis varying with the speed ofrotation, whereby said resistance varies in accordance with said speed.

RAY J. BRIGHT.

